U.S. patent application number 13/349571 was filed with the patent office on 2012-09-27 for three-phase boost-buck power factor correction converter.
This patent application is currently assigned to FSP-POWERLAND TECHNOLOGY INC.. Invention is credited to Peng Mao, Chuanyun Wang, Ming Xu.
Application Number | 20120242299 13/349571 |
Document ID | / |
Family ID | 46859770 |
Filed Date | 2012-09-27 |
United States Patent
Application |
20120242299 |
Kind Code |
A1 |
Xu; Ming ; et al. |
September 27, 2012 |
THREE-PHASE BOOST-BUCK POWER FACTOR CORRECTION CONVERTER
Abstract
A three-phase boost-buck PFC converter including three
independent single-phase boost-buck PFC circuits respectively is
provided, which are capable of performing PFC on each phase of the
three-phase power. The single-phase boost-buck PFC circuit is
composed of two single-phase boost-buck converters independently
working in a positive and a negative half cycle of an input
voltage, and the two single-phase boost-buck converters are
connected in parallel at an input side, and are connected in series
at an output side, and each of the single-phase boost-buck
converters is composed of a front-end boost circuit and a back-end
buck circuit connected in cascade. Compared to the existing
technique, regardless of a boost mode or a buck mode, the
conduction loss is effectively reduced, and the whole system
efficiency is effectively improved.
Inventors: |
Xu; Ming; (Nanjing, CN)
; Wang; Chuanyun; (Nanjing, CN) ; Mao; Peng;
(Nanjing, CN) |
Assignee: |
FSP-POWERLAND TECHNOLOGY
INC.
Nanjing
CN
FSP TECHNOLOGY INC.
Taoyuan County
TW
|
Family ID: |
46859770 |
Appl. No.: |
13/349571 |
Filed: |
January 13, 2012 |
Current U.S.
Class: |
323/210 |
Current CPC
Class: |
H02M 1/4225 20130101;
H02M 1/4216 20130101; Y02B 70/10 20130101; Y02B 70/126
20130101 |
Class at
Publication: |
323/210 |
International
Class: |
G05F 1/70 20060101
G05F001/70 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2011 |
CN |
201110071620.0 |
Claims
1. A three-phase boost-buck power factor correction (PFC)
converter, comprising: a first, a second and a third single-phase
boost-buck PFC circuits, respectively receiving one-phase voltage
of three-phase voltages, and respectively comprising a neutral
point, an input terminal, a first output terminal and a second
output terminal; a first output capacitor, having one end connected
to the three neutral points, and another end connected to the three
first output terminals; a second output capacitor, having one end
connected to the three neutral points, and another end connected to
the three second output terminals; a neutral line, wherein the
three neutral points are connected to the neutral line, wherein the
first, the second and the third single-phase boost-buck PFC
circuits are respectively composed of two single-phase boost-buck
converters independently working in a positive and a negative half
cycle of an input voltage, and the two single-phase boost-buck
converters are connected in parallel at an input side, and are
connected in series at an output side, and each of the single-phase
boost-buck converters is composed of a front-end boost circuit and
a back-end buck circuit connected in cascade.
2. The three-phase boost-buck PFC converter as claimed in claim 1,
wherein each of the first, the second and the third single-phase
boost-buck PFC circuits comprises: a first to a sixth diodes,
wherein an anode of the first diode is connected to an anode of the
third diode, a cathode of the second diode is connected to a
cathode of the fourth diode, and a cathode of the sixth diode and
an anode of the fifth diode are connected to the neutral point; a
first to a fourth switches, each of the switches having a first
terminal and a second terminal, wherein the first terminal of the
first switch and the second terminal of the second switch are
connected to the neutral point, the second terminal of the first
switch is connected to a cathode of the first diode, the first
terminal of the second switch is connected to an anode of the
second diode, the first terminal of the third switch is connected
to a cathode of the fifth diode, the second terminal of the third
switch is connected to a cathode of the third diode, the first
terminal of the fourth switch is connected to an anode of the
fourth diode, and the second terminal of the fourth switch is
connected to an anode of the sixth diode; a first to a fourth
inductors, wherein one end of the first inductor is connected to
the input terminal, another end of the first inductor is connected
to a connection line between the anode of the first diode and the
anode of the third diode, one end of the second inductor is
connected to the input terminal, another end of the second inductor
is connected to a connection line between the cathode of the second
diode and the cathode of the fourth diode, one end of the third
inductor is connected to the first output terminal, another end of
the third inductor is connected to the first terminal of the third
switch, one end of the fourth inductor is connected to the second
output terminal, and another end of the fourth inductor is
connected to the second terminal of the fourth switch; and a first
filter capacitor and a second filter capacitor, wherein one end of
the first filter capacitor is connected to a connection line
between the second terminal of the third switch and the cathode of
the third diode, another end of the first filter capacitor is
connected to the neutral point, one end of the second filter
capacitor is connected to a connection line between the first
terminal of the fourth switch and the anode of the fourth diode,
and another end of the second filter capacitor is connected to the
neutral point.
3. The three-phase boost-buck PFC converter as claimed in claim 2,
wherein the first inductor and the second inductor are magnetically
coupled.
4. The three-phase boost-buck PFC converter as claimed in claim 1,
wherein each of the first, the second and the third single-phase
boost-buck PFC circuits comprises: a first to a sixth diodes,
wherein an anode of the first diode is connected to an anode of the
third diode, a cathode of the second diode is connected to a
cathode of the fourth diode, and a cathode of the sixth diode and
an anode of the fifth diode are connected to the neutral point; a
first to a fourth switches, each of the switches having a first
terminal and a second terminal, wherein the first terminal of the
first switch and the second terminal of the second switch are
connected to the neutral point, the second terminal of the first
switch is connected to a cathode of the first diode, the first
terminal of the second switch is connected to an anode of the
second diode, the first terminal of the third switch is connected
to a cathode of the fifth diode, the second terminal of the third
switch is connected to a cathode of the third diode, the first
terminal of the fourth switch is connected to an anode of the
fourth diode, and the second terminal of the fourth switch is
connected to an anode of the sixth diode; a first to a third
inductors, wherein one end of the first inductor is connected to
the input terminal, another end of the first inductor is
respectively connected to a connection line between the anodes of
the first diode and the third diode and a connection line between
the cathodes of the second diode and the fourth diode, one end of
the second inductor is connected to the first output terminal,
another end of the second inductor is connected to the first
terminal of the third switch, one end of the third inductor is
connected to the second output terminal, and another end of the
third inductor is connected to the second terminal of the fourth
switch; and a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the neutral point, one end of the second
filter capacitor is connected to a connection line between the
first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the neutral point.
5. The three-phase boost-buck PFC converter as claimed in claim 1,
wherein each of the first, the second and the third single-phase
boost-buck PFC circuits comprises: a first to a sixth diodes,
wherein an anode of the first diode is connected to an anode of the
third diode, a cathode of the second diode is connected to a
cathode of the fourth diode, a cathode of the fifth diode is
connected to the first output terminal, an anode of the sixth diode
is connected to the second output terminal, and an anode of the
fifth diode is connected to a cathode of the sixth diode; a first
to a fourth switches, each of the switches having a first terminal
and a second terminal, wherein the first terminal of the first
switch is connected to the second terminal of the second switch,
the second terminal of the first switch is connected to a cathode
of the first diode, the first terminal of the second switch is
connected to an anode of the second diode, the first terminal of
the third switch is connected to a connection line between the
cathode of the fifth diode and the first output terminal, the
second terminal of the third switch is connected to a cathode of
the third diode, the first terminal of the fourth switch is
connected to an anode of the fourth diode, and the second terminal
of the fourth switch is connected to a connection line between the
anode of the sixth diode and the second output terminal; a first to
a third inductors, wherein one end of the first inductor is
connected to the input terminal, another end of the first inductor
is connected to a connection line between the anode of the first
diode and the anode of the third diode, one end of the second
inductor is connected to the input terminal, another end of the
second inductor is connected to a connection line between the
cathode of the second diode and the cathode of the fourth diode,
one end of the third inductor is connected to the neutral point,
and another end of the third inductor is connected to a connection
line between the anode of the fifth diode and the cathode of the
sixth diode and a connection line between the first terminal of the
first switch and the second terminal of the second switch; and a
first filter capacitor and a second filter capacitor, wherein one
end of the first filter capacitor is connected to a connection line
between the second terminal of the third switch and the cathode of
the third diode, another end of the first filter capacitor is
connected to the connection line between the anode of the fifth
diode and the cathode of the sixth diode, one end of the second
filter capacitor is connected to a connection line between the
first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the connection line between the anode of the fifth diode and the
cathode of the sixth diode.
6. The three-phase boost-buck PFC converter as claimed in claim 5,
wherein the first inductor and the second inductor are magnetically
coupled.
7. The three-phase boost-buck PFC converter as claimed in claim 1,
wherein each of the first, the second and the third single-phase
boost-buck PFC circuits comprises: a first to a sixth diodes,
wherein an anode of the first diode is connected to an anode of the
third diode, a cathode of the second diode is connected to a
cathode of the fourth diode, a cathode of the fifth diode is
connected to the first output terminal, an anode of the sixth diode
is connected to the second output terminal, and an anode of the
fifth diode is connected to a cathode of the sixth diode; a first
to a fourth switches, each of the switches having a first terminal
and a second terminal, wherein the first terminal of the first
switch is connected to the second terminal of the second switch,
the second terminal of the first switch is connected to a cathode
of the first diode, the first terminal of the second switch is
connected to an anode of the second diode, the first terminal of
the third switch is connected to a connection line between the
cathode of the fifth diode and the first output terminal, the
second terminal of the third switch is connected to a cathode of
the third diode, the first terminal of the fourth switch is
connected to an anode of the fourth diode, and the second terminal
of the fourth switch is connected to a connection line between the
anode of the sixth diode and the second output terminal; a first
inductor and a second inductor, wherein one end of the first
inductor is connected to the input terminal, another end of the
first inductor is respectively connected to a connection line
between the anodes of the first diode and the third diode, and a
connection line between the cathodes of the second diode and the
fourth diode, one end of the second inductor is connected to the
neutral point, and another end of the second inductor is connected
to a connection line between the anode of the fifth diode and the
cathode of the sixth diode and a connection line between the first
terminal of the first switch and the second terminal of the second
switch; and a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the connection line between the anode of
the fifth diode and the cathode of the sixth diode, one end of the
second filter capacitor is connected to a connection line between
the first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the connection line between the anode of the fifth diode and the
cathode of the sixth diode.
8. A single-phase boost-buck power factor converter (PFC)
converter, comprising: a single-phase boost-buck PFC circuit,
comprising a neutral point, an input terminal, a first output
terminal and a second output terminal; a first output capacitor,
having one end connected to the neutral point, and another end
connected to the first output terminal; a second output capacitor,
having one end connected to the neutral point, and another end
connected to the second output terminal; a neutral line, wherein a
second input terminal is connected to the neutral point, wherein
the single-phase boost-buck PFC circuit is composed of two
single-phase boost-buck converters independently working in a
positive and a negative half cycle of an input voltage, and the two
single-phase boost-buck converters are connected in parallel at an
input side, and are connected in series at an output side, and each
of the single-phase boost-buck converters is composed of a
front-end boost circuit and a back-end buck circuit connected in
cascade.
9. The single-phase boost-buck PFC converter as claimed in claim 8,
wherein the single-phase boost-buck PFC circuit comprises: a first
to a sixth diodes, wherein an anode of the first diode is connected
to an anode of the third diode, a cathode of the second diode is
connected to a cathode of the fourth diode, and a cathode of the
sixth diode and an anode of the fifth diode are connected to the
neutral point; a first to a fourth switches, each of the switches
having a first terminal and a second terminal, wherein the first
terminal of the first switch and the second terminal of the second
switch are connected to the neutral point, the second terminal of
the first switch is connected to a cathode of the first diode, the
first terminal of the second switch is connected to an anode of the
second diode, the first terminal of the third switch is connected
to a cathode of the fifth diode, the second terminal of the third
switch is connected to a cathode of the third diode, the first
terminal of the fourth switch is connected to an anode of the
fourth diode, and the second terminal of the fourth switch is
connected to an anode of the sixth diode; a first to a fourth
inductors, wherein one end of the first inductor is connected to
the input terminal, another end of the first inductor is connected
to a connection line between the anode of the first diode and the
anode of the third diode, one end of the second inductor is
connected to the input terminal, another end of the second inductor
is connected to a connection line between the cathode of the second
diode and the cathode of the fourth diode, one end of the third
inductor is connected to the first output terminal, another end of
the third inductor is connected to the first terminal of the third
switch, one end of the fourth inductor is connected to the second
output terminal, and another end of the fourth inductor is
connected to the second terminal of the fourth switch; and a first
filter capacitor and a second filter capacitor, wherein one end of
the first filter capacitor is connected to a connection line
between the second terminal of the third switch and the cathode of
the third diode, another end of the first filter capacitor is
connected to the neutral point, one end of the second filter
capacitor is connected to a connection line between the first
terminal of the fourth switch and the anode of the fourth diode,
and another end of the second filter capacitor is connected to the
neutral point.
10. The single-phase boost-buck PFC converter as claimed in claim
9, wherein the first inductor and the second inductor are
magnetically coupled.
11. The single-phase boost-buck PFC converter as claimed in claim
8, wherein the single-phase boost-buck PFC circuit comprises: a
first to a sixth diodes, wherein an anode of the first diode is
connected to an anode of the third diode, a cathode of the second
diode is connected to a cathode of the fourth diode, and a cathode
of the sixth diode and an anode of the fifth diode are connected to
the neutral point; a first to a fourth switches, each of the
switches having a first terminal and a second terminal, wherein the
first terminal of the first switch and the second terminal of the
second switch are connected to the neutral point, the second
terminal of the first switch is connected to a cathode of the first
diode, the first terminal of the second switch is connected to an
anode of the second diode, the first terminal of the third switch
is connected to a cathode of the fifth diode, the second terminal
of the third switch is connected to a cathode of the third diode,
the first terminal of the fourth switch is connected to an anode of
the fourth diode, and the second terminal of the fourth switch is
connected to an anode of the sixth diode; a first to a third
inductors, wherein one end of the first inductor is connected to
the input terminal, another end of the first inductor is
respectively connected to a connection line between the anodes of
the first diode and the third diode, and a connection line between
the cathodes of the second diode and the fourth diode, one end of
the second inductor is connected to the first output terminal,
another end of the second inductor is connected to the first
terminal of the third switch, one end of the third inductor is
connected to the second output terminal, and another end of the
third inductor is connected to the second terminal of the fourth
switch; and a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the neutral point, one end of the second
filter capacitor is connected to a connection line between the
first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the neutral point.
12. The single-phase boost-buck PFC converter as claimed in claim
8, wherein the single-phase boost-buck PFC circuit comprises: a
first to a sixth diodes, wherein an anode of the first diode is
connected to an anode of the third diode, a cathode of the second
diode is connected to a cathode of the fourth diode, a cathode of
the fifth diode is connected to the first output terminal, an anode
of the sixth diode is connected to the second output terminal, and
an anode of the fifth diode is connected to a cathode of the sixth
diode; a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch is connected to the second terminal of the second
switch, the second terminal of the first switch is connected to a
cathode of the first diode, the first terminal of the second switch
is connected to an anode of the second diode, the first terminal of
the third switch is connected to a connection line between the
cathode of the fifth diode and the first output terminal, the
second terminal of the third switch is connected to a cathode of
the third diode, the first terminal of the fourth switch is
connected to an anode of the fourth diode, and the second terminal
of the fourth switch is connected to a connection line between the
anode of the sixth diode and the second output terminal; a first to
a third inductors, wherein one end of the first inductor is
connected to the input terminal, another end of the first inductor
is connected to a connection line between the anode of the first
diode and the anode of the third diode, one end of the second
inductor is connected to the input terminal, another end of the
second inductor is connected to a connection line between the
cathode of the second diode and the cathode of the fourth diode,
one end of the third inductor is connected to the neutral point,
and another end of the third inductor is connected to a connection
line between the anode of the fifth diode and the cathode of the
sixth diode and a connection line between the first terminal of the
first switch and the second terminal of the second switch; and a
first filter capacitor and a second filter capacitor, wherein one
end of the first filter capacitor is connected to a connection line
between the second terminal of the third switch and the cathode of
the third diode, another end of the first filter capacitor is
connected to the connection line between the anode of the fifth
diode and the cathode of the sixth diode, one end of the second
filter capacitor is connected to a connection line between the
first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the connection line between the anode of the fifth diode and the
cathode of the sixth diode.
13. The single-phase boost-buck PFC converter as claimed in claim
12, wherein the first inductor and the second inductor are
magnetically coupled.
14. The single-phase boost-buck PFC converter as claimed in claim
8, wherein the single-phase boost-buck PFC circuit comprises: a
first to a sixth diodes, wherein an anode of the first diode is
connected to an anode of the third diode, a cathode of the second
diode is connected to a cathode of the fourth diode, a cathode of
the fifth diode is connected to the first output terminal, an anode
of the sixth diode is connected to the second output terminal, and
an anode of the fifth diode is connected to a cathode of the sixth
diode; a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch is connected to the second terminal of the second
switch, the second terminal of the first switch is connected to a
cathode of the first diode, the first terminal of the second switch
is connected to an anode of the second diode, the first terminal of
the third switch is connected to a connection line between the
cathode of the fifth diode and the first output terminal, the
second terminal of the third switch is connected to a cathode of
the third diode, the first terminal of the fourth switch is
connected to an anode of the fourth diode, and the second terminal
of the fourth switch is connected to a connection line between the
anode of the sixth diode and the second output terminal; a first
inductor and a second inductor, wherein one end of the first
inductor is connected to the input terminal, another end of the
first inductor is respectively connected to a connection line
between the anodes of the first diode and the third diode, and a
connection line between the cathodes of the second diode and the
fourth diode, one end of the second inductor is connected to the
neutral point, and another end of the second inductor is connected
to a connection line between the anode of the fifth diode and the
cathode of the sixth diode and a connection line between the first
terminal of the first switch and the second terminal of the second
switch; and a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the connection line between the anode of
the fifth diode and the cathode of the sixth diode, one end of the
second filter capacitor is connected to a connection line between
the first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the connection line between the anode of the fifth diode and the
cathode of the sixth diode.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority benefit of China
application serial no. 201110071620.0, filed Mar. 24, 2011. The
entirety of the above-mentioned patent application is hereby
incorporated by reference herein and made a part of this
specification.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a three-phase boost-buck power
factor correction (PFC) converter. Particularly, the invention
relates to a converter using three independent single-phase
boost-buck PFC circuits.
[0004] 2. Description of Related Art
[0005] In the past two decades, power electronic technology has
been rapidly developed, and various power electronic devices are
widely used in chemical industry and communications, etc., in which
a rectifier is a most typical one. The conventional rectifiers
include diode rectifiers and phase-controlled rectifiers using
thyristors. Using as a typical non-linear circuit, in operation, an
input current of the rectifier contains a large amount of harmonic
component, which may cause a severe harmonic pollution to the
public utility grid. A power factor correction (PFC) converter can
greatly reduce the harmonic component of the input current to
achieve unit power factor rectification, which draws attentions of
scholars from various nations.
[0006] Presently, a single-phase boost type PFC converter having a
boost function is widely used. Such solution has advantages of
simple circuit structure, continuous input current and small filter
volume, etc., though an application scope thereof is limited,
namely, it is only adapted to occasions when an output voltage is
greater than an input voltage peak. In some cases, the output
voltage is smaller than the input voltage peak, which means that
within a fundamental cycle, the converter not only has a phase of
working in a boost mode but also has a phase of working in a buck
mode. Therefore, the PFC converter that can work in both of the
boost mode and the buck mode has become one of the major subjects
studied by scholars all over the world.
[0007] FIG. 1 is a circuit topology of a conventional single-phase
boost-buck PFC converter. The converter can work in the buck mode
or the boost mode by controlling the switches S1 or S2. When the
switch S1 is constantly turned on and the switch S2 is in a pulse
width modulation (PWM) switch working state, the converter is in
the boost mode, and when the switch S2 is constantly turned off,
and the switch S1 is in the PWM switch working state, the converter
is in the buck mode. This circuit is a single-phase boost-buck
converter which is only adapted to small power applications.
[0008] FIG. 2 is a circuit diagram of an existing two-stage
three-phase boost-buck PFC converter. The converter is composed of
a front-stage three-phase buck PFC converter and a back-stage boost
circuit, which is a three-phase three-wire structure. The
three-phase input currents of the circuit are coupled to each
other, which is complicated in control, and is of no avail for
reducing a total harmonic distortion (THD) of the input
current.
[0009] FIG. 3 is a circuit diagram of an existing three-level three
phase boost-buck PFC converter of a three-phase four-wire
structure. Regarding each phase branch, a half branch is in a
working state in either a positive or a negative half cycle of a
supply voltage, and a working mode thereof (the buck or boost mode)
is determined by a relationship between the input voltage and the
output voltage. When a polarity of the phase voltage is positive,
the upper branch of each phase branch is in the working state. Now,
if the phase voltage is greater than the output voltage, the upper
branch works in the buck mode. Otherwise, it works in the boost
mode. When the polarity of the phase voltage is negative, the lower
branch of each phase branch is in the working state. Now, if an
absolute value of the phase voltage is greater than the output
voltage, the lower branch works in the buck mode. Otherwise, it
works in the boost mode. Such circuit effectively resolves the
problems of narrow application scope and complicate control of the
conventional technique, and avails reducing the total harmonic
distortion of the circuit. However, according to the circuit
topology, it is known that in the buck mode, two diodes have
conduction loss at any time, though in the conventional buck PFC
converter, only one diode has the conduction loss during a period
when the switch is turned off. Therefore, when the circuit topology
of FIG. 3 is used, the more proportion the buck mode occupies, the
greater system loss caused by the diode conduction loss is, which
may significantly reduce the system efficiency. In the boost mode,
one diode has the conduction loss in an inductor energy storage
phase, and two diodes have the conduction loss in a freewheeling
phase, while in the conventional boost PFC converter, only one
diode has the conduction loss in the freewheeling phase, so that
efficiency of the converter is reduced.
SUMMARY OF THE INVENTION
[0010] The invention is directed to a three-phase boost-buck power
factor correction (PFC) converter, which resolves a problem of
large system loss of the conventional technique.
[0011] The invention provides a three-phase boost-buck PFC
converter including a first, a second and a third single-phase
boost-buck PFC circuits respectively receiving one-phase voltage of
three-phase voltages, a first output capacitor, a second output
capacitor and a neutral line; the first, the second and the third
single-phase boost-buck PFC circuits respectively include a neutral
point, an input terminal, a first output terminal and a second
output terminal; one end of the first output capacitor is connected
to the three neutral points, and another end is connected to the
three first output terminals; one end of the second output
capacitor is connected to the three neutral points, and another end
is connected to the three second output terminals; the three
neutral points are connected to the neutral line;
[0012] wherein the first, the second and the third single-phase
boost-buck PFC circuits are respectively composed of two
single-phase boost-buck converters independently working in a
positive and a negative half cycle of an input voltage, and the two
single-phase boost-buck converters are connected in parallel at an
input side, and are connected in series at an output side, and each
of the single-phase boost-buck converters is composed of a
front-end boost circuit and a back-end buck circuit connected in
cascade.
[0013] In a first exemplary implementation of the three-phase
boost-buck PFC converter of the invention, each of the first, the
second and the third single-phase boost-buck PFC circuits
includes:
[0014] a first to a sixth diodes, wherein an anode of the first
diode is connected to an anode of the third diode, a cathode of the
second diode is connected to a cathode of the fourth diode, and a
cathode of the sixth diode and an anode of the fifth diode are
connected to the neutral point;
[0015] a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch and the second terminal of the second switch are
connected to the neutral point, the second terminal of the first
switch is connected to a cathode of the first diode, the first
terminal of the second switch is connected to an anode of the
second diode, the first terminal of the third switch is connected
to a cathode of the fifth diode, the second terminal of the third
switch is connected to a cathode of the third diode, the first
terminal of the fourth switch is connected to an anode of the
fourth diode, and the second terminal of the fourth switch is
connected to an anode of the sixth diode;
[0016] a first to a fourth inductors, wherein one end of the first
inductor is connected to the input terminal, another end of the
first inductor is connected to a connection line between the anode
of the first diode and the anode of the third diode, one end of the
second inductor is connected to the input terminal, another end of
the second inductor is connected to a connection line between the
cathode of the second diode and the cathode of the fourth diode,
one end of the third inductor is connected to the first output
terminal, another end of the third inductor is connected to the
first terminal of the third switch, one end of the fourth inductor
is connected to the second output terminal, and another end of the
fourth inductor is connected to the second terminal of the fourth
switch; and
[0017] a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the neutral point, one end of the second
filter capacitor is connected to a connection line between the
first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the neutral point.
[0018] The first inductor and the second inductor are magnetically
coupled, so that the number of components in the circuit is
reduced, and the circuit structure is more compact.
[0019] In a second exemplary implementation of the three-phase
boost-buck PFC converter of the invention, each of the first, the
second and the third single-phase boost-buck PFC circuits
includes:
[0020] a first to a sixth diodes, wherein an anode of the first
diode is connected to an anode of the third diode, a cathode of the
second diode is connected to a cathode of the fourth diode, and a
cathode of the sixth diode and an anode of the fifth diode are
connected to the neutral point;
[0021] a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch and the second terminal of the second switch are
connected to the neutral point, the second terminal of the first
switch is connected to a cathode of the first diode, the first
terminal of the second switch is connected to an anode of the
second diode, the first terminal of the third switch is connected
to a cathode of the fifth diode, the second terminal of the third
switch is connected to a cathode of the third diode, the first
terminal of the fourth switch is connected to an anode of the
fourth diode, and the second terminal of the fourth switch is
connected to an anode of the sixth diode;
[0022] a first to a third inductors, wherein one end of the first
inductor is connected to the input terminal, another end of the
first inductor is respectively connected to a connection line
between the anodes of the first diode and the third diode, and a
connection line between the cathodes of the second diode and the
fourth diode, one end of the second inductor is connected to the
first output terminal, another end of the second inductor is
connected to the first terminal of the third switch, one end of the
third inductor is connected to the second output terminal, and
another end of the third inductor is connected to the second
terminal of the fourth switch; and
[0023] a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the neutral point, one end of the second
filter capacitor is connected to a connection line between the
first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the neutral point.
[0024] In a third exemplary implementation of the three-phase
boost-buck PFC converter of the invention, each of the first, the
second and the third single-phase boost-buck PFC circuits
includes:
[0025] a first to a sixth diodes, wherein an anode of the first
diode is connected to an anode of the third diode, a cathode of the
second diode is connected to a cathode of the fourth diode, a
cathode of the fifth diode is connected to the first output
terminal, an anode of the sixth diode is connected to the second
output terminal, and an anode of the fifth diode is connected to a
cathode of the sixth diode;
[0026] a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch is connected to the second terminal of the second
switch, the second terminal of the first switch is connected to a
cathode of the first diode, the first terminal of the second switch
is connected to an anode of the second diode, the first terminal of
the third switch is connected to a connection line between the
cathode of the fifth diode and the first output terminal, the
second terminal of the third switch is connected to a cathode of
the third diode, the first terminal of the fourth switch is
connected to an anode of the fourth diode, and the second terminal
of the fourth switch is connected to a connection line between the
anode of the sixth diode and the second output terminal;
[0027] a first to a third inductors, wherein one end of the first
inductor is connected to the input terminal, another end of the
first inductor is connected to a connection line between the anode
of the first diode and the anode of the third diode, one end of the
second inductor is connected to the input terminal, another end of
the second inductor is connected to a connection line between the
cathode of the second diode and the cathode of the fourth diode,
one end of the third inductor is connected to the neutral point,
and another end of the third inductor is connected to a connection
line between the anode of the fifth diode and the cathode of the
sixth diode and a connection line between the first terminal of the
first switch and the second terminal of the second switch; and
[0028] a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the connection line between the anode of
the fifth diode and the cathode of the sixth diode, one end of the
second filter capacitor is connected to a connection line between
the first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the connection line between the anode of the fifth diode and the
cathode of the sixth diode.
[0029] Further, the first inductor and the second inductor are
magnetically coupled.
[0030] In a fourth exemplary implementation of the three-phase
boost-buck PFC converter of the invention, each of the first, the
second and the third single-phase boost-buck PFC circuits
includes:
[0031] a first to a sixth diodes, wherein an anode of the first
diode is connected to an anode of the third diode, a cathode of the
second diode is connected to a cathode of the fourth diode, a
cathode of the fifth diode is connected to the first output
terminal, an anode of the sixth diode is connected to the second
output terminal, and an anode of the fifth diode is connected to a
cathode of the sixth diode;
[0032] a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch is connected to the second terminal of the second
switch, the second terminal of the first switch is connected to a
cathode of the first diode, the first terminal of the second switch
is connected to an anode of the second diode, the first terminal of
the third switch is connected to a connection line between the
cathode of the fifth diode and the first output terminal, the
second terminal of the third switch is connected to a cathode of
the third diode, the first terminal of the fourth switch is
connected to an anode of the fourth diode, and the second terminal
of the fourth switch is connected to a connection line between the
anode of the sixth diode and the second output terminal;
[0033] a first inductor and a second inductor, wherein one end of
the first inductor is connected to the input terminal, another end
of the first inductor is respectively connected to a connection
line between the anodes of the first diode and the third diode, and
a connection line between the cathodes of the second diode and the
fourth diode, one end of the second inductor is connected to the
neutral point, another end of the second inductor is connected to a
connection line between the anode of the fifth diode and the
cathode of the sixth diode and a connection line between the first
terminal of the first switch and the second terminal of the second
switch; and
[0034] a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the connection line between the anode of
the fifth diode and the cathode of the sixth diode, one end of the
second filter capacitor is connected to a connection line between
the first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the connection line between the anode of the fifth diode and the
cathode of the sixth diode.
[0035] The three-phase boost-buck PFC converter of the invention
can be decoupled into three independent single-phase boost-buck PFC
converters, so that according to the spirit of the invention, a
single-phase boost-buck PFC converter is obtained, which
includes:
[0036] a single-phase boost-buck PFC circuit, a first output
capacitor, a second output capacitor and a neutral line; the
single-phase boost-buck PFC circuit includes a neutral point, an
input terminal, a first output terminal and a second output
terminal; one end of the first output capacitor is connected to the
neutral point, and another end is connected to the first output
terminal; one end of the second output capacitor is connected to
the neutral point, and another end is connected to the second
output terminal; a second input terminal is connected to the
neutral point;
[0037] wherein the single-phase boost-buck PFC circuit is composed
of two single-phase boost-buck converters independently working in
a positive and a negative half cycle of an input voltage, and the
two single-phase boost-buck converters are connected in parallel at
an input side, and are connected in series at an output side, and
each of the single-phase boost-buck converters is composed of a
front-end boost circuit and a back-end buck circuit connected in
cascade.
[0038] In a first exemplary implementation of the single-phase
boost-buck PFC converter of the invention, the single-phase
boost-buck PFC circuit includes:
[0039] a first to a sixth diodes, wherein an anode of the first
diode is connected to an anode of the third diode, a cathode of the
second diode is connected to a cathode of the fourth diode, and a
cathode of the sixth diode and an anode of the fifth diode are
connected to the neutral point;
[0040] a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch and the second terminal of the second switch are
connected to the neutral point, the second terminal of the first
switch is connected to a cathode of the first diode, the first
terminal of the second switch is connected to an anode of the
second diode, the first terminal of the third switch is connected
to a cathode of the fifth diode, the second terminal of the third
switch is connected to a cathode of the third diode, the first
terminal of the fourth switch is connected to an anode of the
fourth diode, and the second terminal of the fourth switch is
connected to an anode of the sixth diode;
[0041] a first to a fourth inductors, wherein one end of the first
inductor is connected to the input terminal, another end of the
first inductor is connected to a connection line between the anode
of the first diode and the anode of the third diode, one end of the
second inductor is connected to the input terminal, another end of
the second inductor is connected to a connection line between the
cathode of the second diode and the cathode of the fourth diode,
one end of the third inductor is connected to the first output
terminal, another end of the third inductor is connected to the
first terminal of the third switch, one end of the fourth inductor
is connected to the second output terminal, and another end of the
fourth inductor is connected to the second terminal of the fourth
switch; and
[0042] a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the neutral point, one end of the second
filter capacitor is connected to a connection line between the
first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the neutral point.
[0043] Further, the first inductor and the second inductor are
magnetically coupled.
[0044] In a second exemplary implementation of the single-phase
boost-buck PFC converter of the invention, the single-phase
boost-buck PFC circuit includes:
[0045] a first to a sixth diodes, wherein an anode of the first
diode is connected to an anode of the third diode, a cathode of the
second diode is connected to a cathode of the fourth diode, and a
cathode of the sixth diode and an anode of the fifth diode are
connected to the neutral point;
[0046] a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch and the second terminal of the second switch are
connected to the neutral point, the second terminal of the first
switch is connected to a cathode of the first diode, the first
terminal of the second switch is connected to an anode of the
second diode, the first terminal of the third switch is connected
to a cathode of the fifth diode, the second terminal of the third
switch is connected to a cathode of the third diode, the first
terminal of the fourth switch is connected to an anode of the
fourth diode, and the second terminal of the fourth switch is
connected to an anode of the sixth diode;
[0047] a first to a third inductors, wherein one end of the first
inductor is connected to the input terminal, another end of the
first inductor is respectively connected to a connection line
between the anodes of the first diode and the third diode, and a
connection line between the cathodes of the second diode and the
fourth diode, one end of the second inductor is connected to the
first output terminal, another end of the second inductor is
connected to the first terminal of the third switch, one end of the
third inductor is connected to the second output terminal, and
another end of the third inductor is connected to the second
terminal of the fourth switch; and
[0048] a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the neutral point, one end of the second
filter capacitor is connected to a connection line between the
first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the neutral point.
[0049] In a third exemplary implementation of the single-phase
boost-buck PFC converter of the invention, the single-phase
boost-buck PFC circuit includes:
[0050] a first to a sixth diodes, wherein an anode of the first
diode is connected to an anode of the third diode, a cathode of the
second diode is connected to a cathode of the fourth diode, a
cathode of the fifth diode is connected to the first output
terminal, an anode of the sixth diode is connected to the second
output terminal, and an anode of the fifth diode is connected to a
cathode of the sixth diode;
[0051] a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch is connected to the second terminal of the second
switch, the second terminal of the first switch is connected to a
cathode of the first diode, the first terminal of the second switch
is connected to an anode of the second diode, the first terminal of
the third switch is connected to a connection line between the
cathode of the fifth diode and the first output terminal, the
second terminal of the third switch is connected to a cathode of
the third diode, the first terminal of the fourth switch is
connected to an anode of the fourth diode, and the second terminal
of the fourth switch is connected to a connection line between the
anode of the sixth diode and the second output terminal;
[0052] a first to a third inductors, wherein one end of the first
inductor is connected to the input terminal, another end of the
first inductor is connected to a connection line between the anode
of the first diode and the anode of the third diode, one end of the
second inductor is connected to the input terminal, another end of
the second inductor is connected to a connection line between the
cathode of the second diode and the cathode of the fourth diode,
one end of the third inductor is connected to the neutral point,
and another end of the third inductor is connected to a connection
line between the anode of the fifth diode and the cathode of the
sixth diode and a connection line between the first terminal of the
first switch and the second terminal of the second switch; and
[0053] a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the connection line between the anode of
the fifth diode and the cathode of the sixth diode, one end of the
second filter capacitor is connected to a connection line between
the first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the connection line between the anode of the fifth diode and the
cathode of the sixth diode.
[0054] Further, the first inductor and the second inductor are
magnetically coupled.
[0055] In a fourth exemplary implementation of the single-phase
boost-buck PFC converter of the invention, the single-phase
boost-buck PFC circuit includes:
[0056] a first to a sixth diodes, wherein an anode of the first
diode is connected to an anode of the third diode, a cathode of the
second diode is connected to a cathode of the fourth diode, a
cathode of the fifth diode is connected to the first output
terminal, an anode of the sixth diode is connected to the second
output terminal, and an anode of the fifth diode is connected to a
cathode of the sixth diode;
[0057] a first to a fourth switches, each of the switches having a
first terminal and a second terminal, wherein the first terminal of
the first switch is connected to the second terminal of the second
switch, the second terminal of the first switch is connected to a
cathode of the first diode, the first terminal of the second switch
is connected to an anode of the second diode, the first terminal of
the third switch is connected to a connection line between the
cathode of the fifth diode and the first output terminal, the
second terminal of the third switch is connected to a cathode of
the third diode, the first terminal of the fourth switch is
connected to an anode of the fourth diode, and the second terminal
of the fourth switch is connected to a connection line between the
anode of the sixth diode and the second output terminal;
[0058] a first inductor and a second inductor, wherein one end of
the first inductor is connected to the input terminal, another end
of the first inductor is respectively connected to a connection
line between the anodes of the first diode and the third diode, and
a connection line between the cathodes of the second diode and the
fourth diode, one end of the second inductor is connected to the
neutral point, another end of the second inductor is connected to a
connection line between the anode of the fifth diode and the
cathode of the sixth diode and a connection line between the first
terminal of the first switch and the second terminal of the second
switch; and
[0059] a first filter capacitor and a second filter capacitor,
wherein one end of the first filter capacitor is connected to a
connection line between the second terminal of the third switch and
the cathode of the third diode, another end of the first filter
capacitor is connected to the connection line between the anode of
the fifth diode and the cathode of the sixth diode, one end of the
second filter capacitor is connected to a connection line between
the first terminal of the fourth switch and the anode of the fourth
diode, and another end of the second filter capacitor is connected
to the connection line between the anode of the fifth diode and the
cathode of the sixth diode.
[0060] The three-phase boost-buck PFC converter of the invention
includes three independent single-phase boost-buck PFC circuits
capable of performing power factor correction on each phase of the
three-phase power. The single-phase boost-buck PFC circuit is
composed of two single-phase boost-buck converters independently
working in the positive and negative half cycles of the input
voltage, and the two single-phase boost-buck converters are
connected in parallel at an input side, and are connected in series
at an output side, and each of the single-phase boost-buck
converters is composed of a front-end boost circuit and a back-end
buck circuit connected in cascade. Compared to the existing
technique, regardless of the boost mode or the buck mode, the
conduction loss is effectively reduced, and the whole system
efficiency is effectively improved.
[0061] In order to make the aforementioned and other features and
advantages of the invention comprehensible, several exemplary
implementations accompanied with figures are described in detail
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0062] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention.
[0063] FIG. 1 is a circuit diagram of a conventional single-phase
boost-buck power factor correction (PFC) converter.
[0064] FIG. 2 is a circuit diagram of an existing two-stage
three-phase boost-buck PFC converter.
[0065] FIG. 3 is a circuit diagram of an existing three-level three
phase boost-buck PFC converter of a three-phase four-wire
structure.
[0066] FIG. 4 is a circuit diagram of a first exemplary
implementation of a three-phase boost-buck PFC converter of the
invention.
[0067] FIG. 5 is a circuit diagram of an improved implementation of
the first exemplary implementation of a three-phase boost-buck PFC
converter of the invention.
[0068] FIG. 6 is a circuit diagram of a second exemplary
implementation of a three-phase boost-buck PFC converter of the
invention.
[0069] FIG. 7 is a circuit diagram of a third exemplary
implementation of a three-phase boost-buck PFC converter of the
invention.
[0070] FIG. 8 is a circuit diagram of an improved implementation of
the third exemplary implementation of a three-phase boost-buck PFC
converter of the invention.
[0071] FIG. 9 is a circuit diagram of a fourth exemplary
implementation of a three-phase boost-buck PFC converter of the
invention.
[0072] FIG. 10 is a circuit diagram of a first exemplary
implementation of a single-phase boost-buck PFC converter of the
invention.
[0073] FIG. 11 is a circuit diagram of an improved implementation
of the first exemplary implementation of a single-phase boost-buck
PFC converter of the invention.
[0074] FIG. 12 is a circuit diagram of a second exemplary
implementation of a single-phase boost-buck PFC converter of the
invention.
[0075] FIG. 13 is a circuit diagram of a third exemplary
implementation of a single-phase boost-buck PFC converter of the
invention.
[0076] FIG. 14 is a circuit diagram of an improved implementation
of the third exemplary implementation of a single-phase boost-buck
PFC converter of the invention.
[0077] FIG. 15 is a circuit diagram of a fourth exemplary
implementation of a single-phase boost-buck PFC converter of the
invention.
[0078] FIG. 16 is a decomposition diagram of the first exemplary
implementation of the single-phase boost-buck PFC converter of the
invention.
[0079] FIG. 17 is a schematic diagram of a single-phase boost-buck
PFC converter in a boost mode during a positive half cycle of a
power voltage, in which diagram (a) illustrates a working state
when a switch S1 is turned on, and diagram (b) illustrates a
working state when the switch S1 is turned off.
[0080] FIG. 18 is a schematic diagram of a single-phase boost-buck
PFC converter in a buck mode during a positive half cycle of a
power voltage, in which diagram (a) illustrates a working state
when a switch S3 is turned on, and diagram (b) illustrates a
working state when the switch S3 is turned off.
[0081] FIG. 19 is a schematic diagram of a single-phase boost-buck
PFC converter in a boost mode during a negative half cycle of a
power voltage, in which diagram (a) illustrates a working state
when a switch S2 is turned on, and diagram (b) illustrates a
working state when the switch S2 is turned off.
[0082] FIG. 20 is a schematic diagram of a single-phase boost-buck
PFC converter in a buck mode during a negative half cycle of a
power voltage, in which diagram (a) illustrates a working state
when a switch S4 is turned on, and diagram (b) illustrates a
working state when the switch S4 is turned off.
[0083] FIG. 21 is a control block diagram of a single-phase
boost-buck PFC converter of the invention, in which Qs1-Qs4 are
respectively gate driving signals of switches S1-S4.
DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS
[0084] The exemplary embodiments of the disclosure are illustrated
in detail below with reference to the accompanying drawings. In
addition, components/members of the same reference numerals are
used to represent the same or similar parts in the accompanying
drawings and implementations wherever it is possible.
[0085] Technical details of the invention are described below with
reference of figures.
[0086] The three-phase boost-buck power factor correction (PFC)
converter of the invention includes three independent single-phase
boost-buck PFC circuits, and each of the single-phase boost-buck
PFC circuits is composed of a front-end boost circuit and a
back-end buck circuit connected in cascade.
[0087] In a first exemplary implementation of the three-phase
boost-buck PFC converter of the invention, as shown in FIG. 4, it
includes a first, a second and a third single-phase boost-buck PFC
circuits respectively receiving one-phase voltage of three-phase
voltages (Va, Vb and Vc), a first output capacitor Co1, a second
output capacitor Co2 and a neutral line N. The first, the second
and the third single-phase boost-buck PFC circuits respectively
include a neutral point, an input terminal, a first output terminal
and a second output terminal. One end of the first output capacitor
Co1 is connected to the three neutral points, and another end is
connected to the three first output terminals. One end of the
second output capacitor Co2 is connected to the three neutral
points, and another end is connected to the three second output
terminals. The three neutral points are connected to the neutral
line N. The three-phase boost-buck PFC converter further includes
diodes Da1-Da6, Db1-Db6 and Dc1-Dc6, switches Sa1-Sa4, Sb1-Sb4 and
Sc1-Sc4, inductors La1-La4, Lb1-Lb4 and Lc1-Lc4, and filter
capacitors Ca1-Ca2, Cb1-Cb2 and Cc1-CC2, which are coupled in a
manner as that shown in FIG. 4.
[0088] To be specific, the single-phase boost-buck PFC circuit
receiving the phase voltage Va includes the diodes Da1-Da6, the
switches Sa1-Sa4, the inductors La1-La4, and the filter capacitors
Ca1-Ca2. An anode of the diode Da1 is connected to an anode of the
diode Da3, a cathode of the diode Da2 is connected to a cathode of
the diode Da4, and a cathode of the diode Da6 and an anode of the
diode Da5 are connected to the neutral point. Each of the switches
Sa1-Sa4 has a first terminal and a second terminal. The first
terminal of the switch Sa1 and the second terminal of the switch
Sa2 are connected to the neutral point. The second terminal of the
switch Sa1 is connected to a cathode of the diode Da1, the first
terminal of the switch Sa2 is connected to an anode of the diode
Da2. The first terminal of the switch Sa3 is connected to a cathode
of the diode Da5, the second terminal of the switch Sa3 is
connected to a cathode of the diode Da3. The first terminal of the
switch Sa4 is connected to an anode of the diode Da4, and the
second terminal of the switch Sa4 is connected to an anode of the
diode Da6. One end of the inductor La1 is connected to the input
terminal, another end of the inductor La1 is connected to a
connection line between the anodes of the diodes Da1 and Da3. One
end of the inductor La2 is connected to the input terminal, another
end of the inductor La2 is connected to a connection line between
the cathodes of the diodes Da2 and Da4. One end of the inductor La3
is connected to the first output terminal, another end of the
inductor La3 is connected to the first terminal of the switch Sa3.
One end of the inductor La4 is connected to the second output
terminal, and another end of the inductor La4 is connected to the
second terminal of the switch Sa4. One end of the filter capacitor
Ca1 is connected to a connection line between the second terminal
of the switch Sa3 and the cathode of the diode Da3, another end of
the filter capacitor Ca1 is connected to the neutral point. One end
of the filter capacitor Ca2 is connected to a connection line
between the first terminal of the switch Sa4 and the anode of the
diode Da4, and another end of the filter capacitor Ca2 is connected
to the neutral point.
[0089] In addition, the single-phase boost-buck PFC circuit
receiving the phase voltage Vb includes the diodes Db1-Db6, the
switches Sb1-Sb4, the inductors Lb1-Lb4, and the filter capacitors
Cb1-Cb2. An anode of the diode Db1 is connected to an anode of the
diode Db3, a cathode of the diode Db2 is connected to a cathode of
the diode Db4, and a cathode of the diode Db6 and an anode of the
diode Db5 are connected to the neutral point. Each of the switches
Sb1-Sb4 has a first terminal and a second terminal. The first
terminal of the switch Sb1 and the second terminal of the switch
Sb2 are connected to the neutral point. The second terminal of the
switch Sb1 is connected to a cathode of the diode Db1, the first
terminal of the switch Sb2 is connected to an anode of the diode
Db2. The first terminal of the switch Sb3 is connected to a cathode
of the diode Db5, the second terminal of the switch Sb3 is
connected to a cathode of the diode Db3. The first terminal of the
switch Sb4 is connected to an anode of the diode Db4, and the
second terminal of the switch Sb4 is connected to an anode of the
diode Db6. One end of the inductor Lb1 is connected to the input
terminal, another end of the inductor Lb1 is connected to a
connection line between the anodes of the diodes Db1 and Db3. One
end of the inductor Lb2 is connected to the input terminal, another
end of the inductor Lb2 is connected to a connection line between
the cathodes of the diodes Db2 and Db4. One end of the inductor Lb3
is connected to the first output terminal, another end of the
inductor Lb3 is connected to the first terminal of the switch Sb3.
One end of the inductor Lb4 is connected to the second output
terminal, and another end of the inductor Lb4 is connected to the
second terminal of the switch Sb4. One end of the filter capacitor
Cb1 is connected to a connection line between the second terminal
of the switch Sb3 and the cathode of the diode Db3, another end of
the filter capacitor Cb1 is connected to the neutral point. One end
of the filter capacitor Cb2 is connected to a connection line
between the first terminal of the switch Sb4 and the anode of the
diode Db4, and another end of the filter capacitor Cb2 is connected
to the neutral point.
[0090] Furthermore, the single-phase boost-buck PFC circuit
receiving the phase voltage Vc includes the diodes Dc1-Dc6, the
switches Sc1-Sc4, the inductors Lc1-Lc4, and the filter capacitors
Cc1-Cc2. An anode of the diode Dc1 is connected to an anode of the
diode Dc3, a cathode of the diode Dc2 is connected to a cathode of
the diode Dc4, and a cathode of the diode Dc6 and an anode of the
diode Dc5 are connected to the neutral point. Each of the switches
Sc1-Sc4 has a first terminal and a second terminal. The first
terminal of the switch Sc1 and the second terminal of the switch
Sc2 are connected to the neutral point. The second terminal of the
switch Sc1 is connected to a cathode of the diode Dc1, the first
terminal of the switch Sc2 is connected to an anode of the diode
Dc2. The first terminal of the switch Sc3 is connected to a cathode
of the diode Dc5, the second terminal of the switch Sc3 is
connected to a cathode of the diode Dc3. The first terminal of the
switch Sc4 is connected to an anode of the diode Dc4, and the
second terminal of the switch Sc4 is connected to an anode of the
diode Dc6. One end of the inductor Lc1 is connected to the input
terminal, another end of the inductor Lc1 is connected to a
connection line between the anodes of the diodes Dc1 and Dc3. One
end of the inductor Lc2 is connected to the input terminal, another
end of the inductor Lc2 is connected to a connection line between
the cathodes of the diodes Dc2 and Dc4. One end of the inductor Lc3
is connected to the first output terminal, another end of the
inductor Lc3 is connected to the first terminal of the switch Sc3.
One end of the inductor Lc4 is connected to the second output
terminal, and another end of the inductor Lc4 is connected to the
second terminal of the switch Sc4. One end of the filter capacitor
Cc1 is connected to a connection line between the second terminal
of the switch Sc3 and the cathode of the diode Dc3, another end of
the filter capacitor Cc1 is connected to the neutral point. One end
of the filter capacitor Cc2 is connected to a connection line
between the first terminal of the switch Sc4 and the anode of the
diode Dc4, and another end of the filter capacitor Cc2 is connected
to the neutral point.
[0091] An improved implementation of the first exemplary
implementation of the three-phase boost-buck PFC converter is as
that shown in FIG. 5, in which the inductors La1 and La2, Lb1 and
Lb2, Lc1 and Lc2 are magnetically coupled respectively, i.e. two
inductors share a common magnetic core, and the other parts are the
same to that shown in FIG. 4.
[0092] A second exemplary implementation of the three-phase
boost-buck PFC converter of the invention is as that shown in FIG.
6, in which the inductors La1, Lb1 and Lc1 respectively replace the
inductors La1 and La2, Lb1 and Lb2, Lc1 and Lc2 in the circuit of
FIG. 4, so that the whole circuit is simplified, and the number of
used devices is reduced. A device coupling method is as that shown
in FIG. 6. The difference between FIGS. 4 and 6 is that, in the
embodiment as shown in FIG. 6, one end of the inductor Lx1 (x=a, b,
c) is connected to the input terminal; and another end of the
inductor Lx1 is respectively connected to a connection line between
the anodes of the diodes Dx1 and Dx3 and a connection line between
the cathodes of the diodes Dx2 and Dx4. Moreover, the other parts
of the circuit are the same to that shown in FIG. 4.
[0093] A third exemplary implementation of the three-phase
boost-buck PFC converter of the invention is as that shown in FIG.
7, in which the inductors La3, Lb3 and Lc3 respectively replace the
inductors La3 and La4, Lb3 and Lb4, Lc3 and Lc4 in the circuit of
FIG. 4, so that the whole circuit is simplified, and the number of
the used devices is reduced. A device coupling method is as that
shown in FIG. 7. The difference between FIGS. 4 and 7 is that, in
the embodiment as shown in FIG. 7, three connection lines
respectively between the switches Sx1 (x=a, b, c) and Sx2, between
the filter capacitors Cx1 and Cx2, and between the diodes Dx5 and
Dx6 are connected to the neutral point through the inductor Lx3;
the cathode of the diode Dx5 is connected to the first output
terminal; and the anode of the diode Dx6 is connected to the second
output terminal. Moreover, the other parts of the circuit are the
same to that shown in FIG. 4.
[0094] An improved implementation of the first exemplary
implementation of the three-phase boost-buck PFC converter is as
that shown in FIG. 8, in which the inductors La1 and La2, Lb1 and
Lb2, Lc1 and Lc2 are magnetically coupled respectively, i.e. two
inductors share a common magnetic core, and the other parts are the
same to that shown in FIG. 7.
[0095] A fourth exemplary implementation of the three-phase
boost-buck PFC converter of the invention is as that shown in FIG.
9, in which the inductors La1, Lb1 and Lc1 respectively replace the
inductors La1 and La2, Lb1 and Lb2, Lc1 and Lc2 in the circuit of
FIG. 4, and the inductors La2, Lb2 and Lc2 respectively replace the
inductors La3 and La4, Lb3 and Lb4, Lc3 and Lc4 in the circuit of
FIG. 4, so that the whole circuit is simplified, and the number of
used devices is reduced. A device coupling method is as that shown
in FIG. 9. The difference between FIGS. 4 and 9 is that, in the
embodiment as shown in FIG. 9, one end of the inductor Lx1 (x=a, b,
c) is connected to the input terminal; another end of the inductor
Lx1 is respectively connected to a connection line between the
anodes of the diodes Dx1 and Dx3 and a connection line between the
cathodes of the diodes Dx2 and Dx4; three connection lines
respectively between the switches Sx1 (x=a, b, c) and Sx2, between
the filter capacitors Cx1 and Cx2, and between the diodes Dx5 and
Dx6 are connected to the neutral point through the inductor Lx2;
the cathode of the diode Dx5 is connected to the first output
terminal; and the anode of the diode Dx6 is connected to the second
output terminal. Moreover, the other parts of the circuit are the
same to that shown in FIG. 4.
[0096] Each of the circuits shown in FIGS. 4-9 can be decoupled
into three independent single-phase boost-buck PFC converters, so
that a single-phase boost-buck PFC converter is obtained, which
includes a single-phase boost-buck PFC circuit, a first output
capacitor, a second output capacitor and a neutral line; the
single-phase boost-buck PFC circuit includes a neutral point, an
input terminal, a first output terminal and a second output
terminal. One end of the first output capacitor is connected to the
neutral point, and another end is connected to the first output
terminal. One end of the second output capacitor is connected to
the neutral point, and another end is connected to the second
output terminal. A second input terminal is connected to the
neutral point. The single-phase boost-buck PFC circuit is composed
of a front-end boost circuit and a back-end buck circuit connected
in cascade, i.e. the single-phase boost-buck PFC circuit is a
boos-buck PFC circuit.
[0097] Similarly, six exemplary implementations of the single-phase
boost-buck PFC circuit are obtained with reference of FIGS.
10-15.
[0098] Since the three-phase boost-buck PFC converter of the
invention can be decoupled into three independent single-phase
boost-buck PFC converters having the same basic principle and
working process, only the single-phase boost-buck PFC converter
shown in FIG. 10 is taken as an example to describe the principles
and the working processes of the three-phase boost-buck PFC
converter and the single-phase boost-buck PFC converter of the
invention.
[0099] The single-phase boost-buck PFC converter of FIG. 10 can be
decomposed into two symmetric branches as that shown in FIG. 16,
i.e. an upper branch connected in solid lines and a lower branch
connected in dash lines, and the number and types of the devices in
the upper and lower branches are totally the same. Taking the upper
branch as an example, the upper branch includes two inductors L1
and L3, two switches S1 and S3, three diodes D1, D3 and D5, and two
filter capacitors C1 and Co1.
[0100] If an input voltage is v.sub.in, voltages on the output
capacitors Co1 and Co2 are respectively v.sub.o1 and v.sub.o2, the
working process of the converter can be described as follows:
[0101] 1) when v.sub.in>0, i.e. within a positive half cycle of
the input voltage, the upper branch of the single-phase boost-buck
PFC converter is in a working state, and the working state can be
described as follows: [0102] when v.sub.in<v.sub.o1, the upper
branch works in a boost mode, and in such phase, the switch S3 is
in a constant turn-on state, the diode D5 is in a turn-off state,
and the switch S1 is in a pulse width modulation (PWM) switch
working state: during a period that the switch S1 is turned on, the
inductor L1 stores energy, an [0103] inductor current i.sub.L1 is
increased, the diodes D3 and D5 are turned off, and a current path
is as that shown in FIG. 17(a); during a period that the switch S1
is turned off, the diode D3 is turned on, the diode D5 is turned
off, and a current path is as that shown in FIG. 17(b); [0104] when
v.sub.in>v.sub.o1, the upper branch works in a buck mode, and in
such phase, the switch S1 is in a constant turn-off state, the
diode D3 is in a constant turn-on state, and the switch S3 is in
the PWM switch working state: during a period that the switch S3 is
turned on, the AC power directly transmits power to a load side,
the diode D5 is turned off, and a current path is as that shown in
FIG. 18(a); during a period that the switch S3 is turned off, the
inductor L3 is freewheeled through the diode D5, and a current path
is as that shown in FIG. 18(b). [0105] 2) when v.sub.in<0, i.e.
within a negative half cycle of the input voltage, the lower branch
of the converter is in the working state, and the working state can
be described as follows: [0106] when v.sub.in<v.sub.o1, the
lower branch works in the boost mode, and in such phase, the switch
S4 is in the constant turn-on state, and the switch S2 is in the
PWM switch working state: during a period that the switch S2 is
turned on, an inductor current i.sub.L2 is increased, the diodes D4
and D6 are turned off, and a current path is as that shown in FIG.
19(a); during a period that the switch S2 is turned off, the diode
D4 is turned on, the diode D6 is turned off, and a current path is
as that shown in FIG. 19(b); [0107] when v.sub.in>v.sub.o2, the
upper branch works in the buck mode, and in such phase, the switch
S2 is in the constant turn-off state, and the switch S4 is in the
PWM switch working state: during a period that the switch S4 is
turned on, the AC power directly transmits power to the load side,
an absolute value of the inductor current I.sub.L2 is increased,
the diode D6 is turned off, and a current path is as that shown in
FIG. 20(a); during a period that the switch S4 is turned off, the
inductor L4 is freewheeled through the diode D6 to charge the
output capacitor Co2, and a current path is as that shown in FIG.
20(b).
[0108] FIG. 21 is a control block diagram of the single-phase
boost-buck PFC converter of FIG. 10, in which a double loop control
structure of outer voltage and inner current is used. In order to
control the output voltage to a fixed value and implement power
factor correction of an input side, the output voltage and the
inductor current of the input side are required to be sampled.
Moreover, to assist distributing switch control pulses and generate
a reference signal of the input current, the power voltage is
required to be sampled, and a control principle thereof is as
follows.
[0109] First, the output voltage is sampled, and a difference
between an output voltage reference v.sub.ref and an actual output
voltage is calculated, and the difference is transmitted to a
voltage controller PI_vout, which is generally a
proportional-integral controller, i.e. a PI controller. Then, the
output voltage of the voltage controller and a sampling value of
the input voltage are multiplied to obtain an input current
reference signal i.sub.ref. Then, differences of the current
reference and sampling values of the input currents are calculated,
and after PI operations, the output of the controller can serve as
a modulation wave, and finally the modulation wave and a carrier
wave are intersected to produce the control pulses.
[0110] Compared to the conventional technique, the three-phase and
single-phase boost-buck PFC converters of the invention can
effectively improve system efficiency. An A-phase branch of the
positive half cycle of the power voltage is taken as an example to
compare the three-phase boost-buck PFC converter of the invention
(shown in FIG. 4) with the circuit of FIG. 3.
[0111] In case of the boost mode (a switch Sa1 of FIG. 3 is
constantly turned on, and the switch Sa3 of FIG. 4 is constantly
turned on):
[0112] Regarding the circuit of FIG. 3, during a period when a
switch Sa3 is turned on, the switches Sa1 and Sa3 and a diode Ba1
have the conduction loss. Regarding the circuit of FIG. 4, during a
period when the switch Sa1 is turned on, the switches Sa1 and Sa3
and the diode Da1 have the conduction loss. Therefore, in such
phase, switch types and numbers of the switches of the two circuits
related to the conduction loss are equivalent, so that the
conduction losses thereof are almost equivalent.
[0113] Regarding the circuit of FIG. 3, when the switch Sa3 is
turned off, the diodes Da1 and Da3 have the conduction loss.
Regarding the circuit of FIG. 4, when the switch Sa1 is turned off,
the diode Da3 and the switch Sa3 have the conduction loss.
Therefore, in such phase, although the number of the switch devices
of the two circuits related to the conduction loss are equivalent,
in the circuit of FIG. 4, one switch and one diode are related to
the conduction loss, and in the circuit topology of FIG. 3, two
diodes are related to the conduction loss. Generally, an on-state
resistance of the diode is greater than an on-state resistance of
the switch, so that in case that the same current flows there
through, the conduction loss of the diode is greater than that of
the switch. Therefore, the circuit of FIG. 4 may have higher
efficiency in such phase.
[0114] In case of the buck mode (the switch Sa3 of FIG. 3 is
constantly turned off, and the switch Sa1 of FIG. 4 is constantly
turned off):
[0115] Regarding the circuit of FIG. 3, during a period when the
switch Sa1 is turned on, the switch Sa1 and the diodes Ba1 and Da3
have the conduction loss. Regarding the circuit of FIG. 4, during a
period when the switch Sa3 is turned on, only the switch Sa3 and
the diode Da3 have the conduction loss. Therefore, in such phase,
compared to the circuit of FIG. 3, the circuit topology of FIG. 4
is reduced by the conduction loss of one diode, by which the system
efficiency is improved.
[0116] Regarding the circuit of FIG. 3, during a period when the
switch Sa1 is turned off, the diodes Da1 and Da3 have the
conduction loss. Regarding the circuit of FIG. 4, during a period
when the switch Sa3 is turned off, the diodes Da3 and Da5 have the
conduction loss. Therefore, in such phase, switch types and numbers
of the switch devices of the two circuits related to the conduction
loss are equivalent, so that the conduction losses thereof are
almost equivalent.
[0117] According to the above analysis, it is known that regardless
of the boost mode or the buck mode, the circuit topology of FIG. 4
has higher efficiency, which is very important in a large-capacity
UPS power system.
[0118] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
invention without departing from the scope or spirit of the
invention. In view of the foregoing, it is intended that the
invention cover modifications and variations of this invention
provided they fall within the scope of the following claims and
their equivalents.
* * * * *